The queen of crime fiction: Agatha Christie, pictured in 1946 at her home in Devon. Photograph: Popperfoto

Sometimes, I try to read novels in which solving a mystery is not the driving force propelling the reader forward. This can occasionally be OK – if there's enough relationship intrigue of the betrayal-and-adultery ilk – but generally I prefer novels that make me desperate to find out who did what and why. It's thanks to Agatha Christie, whose novels I became addicted to at the age of 12 and have remained addicted to ever since, that I love crime fiction. I still believe she is the all-time queen of the genre, and I doubt she'll ever be dethroned.

Some denigrate Christie's style and say she lacks depth; they say, "Oh, she's a brilliant plotter, and her puzzles are great, but that's about it." What these detractors fail to acknowledge is just how good at plot and puzzle Christie is, and, more crucially, how important the puzzle element is in crime fiction. It isn't a shallow, low-brow pleasure, to be eschewed in favour of more worthy ingredients such as political comment and psychological depth; puzzle is the most important component of any great story.

Puzzles arise as a direct result of psychological depth, because people hide things and have secret fears and neuroses. Solving the puzzles of individual people and how they interrelate is the single most useful activity you can engage in if your aim is to arrive at a deeper understanding of the world and human nature.

Crime novels with apparently impossible-to-solve puzzles as their focal point resonate so powerfully with readers because they reflect what we know in our deepest hearts to be true: that not knowing the answers to our most urgent questions is the main driving force that propels most people through life. Every time Hercule Poirot mutters: "But it is impossible, mon ami. How can it be so?", we are reminded of how we've felt so often in our lives – at a loss. Christie's psychological insight is profound, and is present in the formal structures of her novels as much as it is in Poirot's or Miss Marple's shrewd one-line analyses of motives for murder.